feat: git::Repository cancellation support (#1288)

feat: `git::Repository` support cancellation.

To make sure users can cancel git operation via signal, e.g. when the
git operation fail or users no longer want to install.

Signed-off-by: Jiahao XU <Jiahao_XU@outlook.com>

crates/binstalk-downloader/Cargo.toml

@@ -17,6 +17,7 @@ binstalk-types = { version = "0.5.0", path = "../binstalk-types" }
 bytes = "1.4.0"
 bzip2 = "0.4.4"
 compact_str = "0.7.0"
+derive_destructure2 = "0.1"
 flate2 = { version = "1.0.26", default-features = false }
 futures-util = "0.3.28"
 generic-array = "0.14.7"

crates/binstalk-downloader/src/git.rs

@@ -1,6 +1,5 @@
 use std::{fmt, mem, num::NonZeroU32, path::Path, str::FromStr, sync::atomic::AtomicBool};
 
-use compact_str::CompactString;
 use gix::{clone, create, open, remote, Url};
 use thiserror::Error as ThisError;
 use tracing::debug;
@@ -8,6 +7,9 @@ use tracing::debug;
 mod progress_tracing;
 use progress_tracing::TracingProgress;
 
+mod cancellation_token;
+pub use cancellation_token::{GitCancelOnDrop, GitCancellationToken};
+
 pub use gix::url::parse::Error as GitUrlParseError;
 
 #[derive(Debug, ThisError)]
@@ -116,14 +118,21 @@ impl Repository {
     /// async context then you must wrap the call in [`tokio::task::spawn_blocking`].
     ///
     /// WARNING: This function must be called after tokio runtime is initialized.
-    pub fn shallow_clone_bare(url: GitUrl, path: &Path) -> Result<Self, GitError> {
+    pub fn shallow_clone_bare(
+        url: GitUrl,
+        path: &Path,
+        cancellation_token: Option<GitCancellationToken>,
+    ) -> Result<Self, GitError> {
         debug!("Shallow cloning {url} to {}", path.display());
 
         Ok(Self(
             Self::prepare_fetch(url, path, create::Kind::Bare)?
                 .fetch_only(
-                    &mut TracingProgress::new(CompactString::new("Cloning")),
-                    &AtomicBool::new(false),
+                    &mut TracingProgress::new("Cloning bare"),
+                    cancellation_token
+                        .as_ref()
+                        .map(GitCancellationToken::get_atomic)
+                        .unwrap_or(&AtomicBool::new(false)),
                 )?
                 .0
                 .into(),
@@ -134,16 +143,26 @@ impl Repository {
     /// async context then you must wrap the call in [`tokio::task::spawn_blocking`].
     ///
     /// WARNING: This function must be called after tokio runtime is initialized.
-    pub fn shallow_clone(url: GitUrl, path: &Path) -> Result<Self, GitError> {
+    pub fn shallow_clone(
+        url: GitUrl,
+        path: &Path,
+        cancellation_token: Option<GitCancellationToken>,
+    ) -> Result<Self, GitError> {
         debug!("Shallow cloning {url} to {} with worktree", path.display());
 
-        let mut progress = TracingProgress::new(CompactString::new("Cloning"));
+        let mut progress = TracingProgress::new("Cloning with worktree");
 
         Ok(Self(
             Self::prepare_fetch(url, path, create::Kind::WithWorktree)?
                 .fetch_then_checkout(&mut progress, &AtomicBool::new(false))?
                 .0
-                .main_worktree(&mut progress, &AtomicBool::new(false))?
+                .main_worktree(
+                    &mut progress,
+                    cancellation_token
+                        .as_ref()
+                        .map(GitCancellationToken::get_atomic)
+                        .unwrap_or(&AtomicBool::new(false)),
+                )?
                 .0
                 .into(),
         ))

crates/binstalk-downloader/src/git/cancellation_token.rs

@@ -0,0 +1,44 @@
+use std::sync::{
+    atomic::{AtomicBool, Ordering::Relaxed},
+    Arc,
+};
+
+use derive_destructure2::destructure;
+
+/// Token that can be used to cancel git operation.
+#[derive(Clone, Debug, Default)]
+pub struct GitCancellationToken(Arc<AtomicBool>);
+
+impl GitCancellationToken {
+    /// Create a guard that cancel the git operation on drop.
+    #[must_use = "You must assign the guard to a variable, \
+otherwise it is equivalent to `GitCancellationToken::cancel()`"]
+    pub fn cancel_on_drop(self) -> GitCancelOnDrop {
+        GitCancelOnDrop(self)
+    }
+
+    /// Cancel the git operation.
+    pub fn cancel(&self) {
+        self.0.store(true, Relaxed)
+    }
+
+    pub(super) fn get_atomic(&self) -> &AtomicBool {
+        &self.0
+    }
+}
+
+/// Guard used to cancel git operation on drop
+#[derive(Debug, destructure)]
+pub struct GitCancelOnDrop(GitCancellationToken);
+
+impl Drop for GitCancelOnDrop {
+    fn drop(&mut self) {
+        self.0.cancel()
+    }
+}
+impl GitCancelOnDrop {
+    /// Disarm the guard, return the token.
+    pub fn disarm(self) -> GitCancellationToken {
+        self.destructure().0
+    }
+}

crates/binstalk-downloader/src/git/progress_tracing.rs

@@ -27,7 +27,7 @@ const SEP: &str = "::";
 
 impl TracingProgress {
     /// Create a new instanCompactce from `name`.
-    pub fn new(name: CompactString) -> Self {
+    pub fn new(name: &str) -> Self {
         let trigger = Arc::new(AtomicBool::new(true));
         tokio::spawn({
             let mut interval = time::interval(Duration::from_secs_f32(EMIT_LOG_EVERY_S));
@@ -43,7 +43,7 @@ impl TracingProgress {
             }
         });
         Self {
-            name,
+            name: CompactString::new(name),
             id: UNKNOWN,
             max: None,
             step: 0,